/Engine/Plugins/Runtime/GameplayAbilities/Source/GameplayAbilities/Public/GameplayEffect.h
Receive a notify that this GameplayEffect has been executed (it must be instant, as it is not added to the Container). Since it is not added to the container, it will not have an associatedFActiveGameplayEffect, just theFGameplayEffectSpec.
void OnExecuted ( [FActiveGameplayEffectsContainer](API\Plugins\GameplayAbilities\FActiveGameplayEffectsContainer) & ActiveGEContainer, [FGameplayEffectSpec](API\Plugins\GameplayAbilities\FGameplayEffectSpec) & GESpec, [FPredictionKey](API\Plugins\GameplayAbilities\FPredictionKey) & PredictionKey ) const